Human genetic studies have greatly accelerated progress in understanding the etiopathogenesis of Parkinson's disease (PD). To date, six causal genes (SNCA, PARK2, PINK1, DJ-1, LRRK2, and VPS35) and ninety susceptibility genes/loci (e.g., MAPT, GBA) have been identified for PD, mostly in populations of European or Asian ancestry. However, these genes explain only a small proportion of PD heritability. Thus, additional novel genes await discovery, and we believe that the highest likelihood of success is in understudied populations such as those of from Latin America. To fill in this gap we created the Latin American Research Consortium on the Genetics of PD (LARGE-PD), a growing collaboration between thirty two institutions in eleven countries across South America/Caribe (Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Honduras, Mexico, Peru, Puerto Rico and Uruguay). LARGE-PD is the largest PD case-control sample series in Latin America (3,857 individuals), with a target to include at least 8,000 individuals in by 2021, thus serving as a unique resource for genetic analysis in this understudied population. As LARGE-PD has progressed, several multiplex PD families (with three or more affected individuals) have been identified and enrolled. With the goal of replicating our preliminary findings and identifying novel risk-modifying variants we propose in Aim 1 to perform a Genome-Wide Association Study (GWAS) in an additional 6,000 cases and healthy controls (1:1) ascertained through LARGE-PD. Our preliminary study in a subset of LARGE-PD (N=1,498) identified 7 interesting novel candidate loci. Genotyping this additional 6,000 individuals (N= 7,498) allows replication of these findings and quadruples our statistical power to find novel associations. We will also perform the first trans-ethnic GWAS in collaboration with the largest European consortium. In Aim 2, we will perform Whole- Genome Sequencing (WGS) in 25 LARGE-PD families negative for mutations in all known PD-genes. Finally, in Aim 3 we will use all our data to generate and test a Latino specific Polygenic Risk Score (PRS), which will account for possible additive effects between all associated variants and will help improve PD risk prediction in this population. This project will identify novel PD genes associated with both familial and sporadic forms of PD using an understudied population, thus improving our knowledge of the etiopatogenesis of the disease and identifying novel therapeutic targets for the treatment of PD, not only in Latin America, but also in other countries with a growing Latino population such as the US. We will also test the validity of current PD risk prediction, based on European populations, in Latinos and generate a Latino specific risk score using our data. We also believe that our study and others like it, will reduce existing health disparities by allowing Latinos to be active participants in clinical trials and novel treatments designed to protect and/or treat individuals with specific genetic variants, the so called personalized medicine. .